/*
 * Copyright 2002-2015 the original author or authors.
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *      http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

package com.bangcommunity.bbframe.common.utils.lang;

import java.lang.reflect.Array;
import java.math.BigDecimal;
import java.math.BigInteger;
import java.text.DecimalFormat;
import java.text.NumberFormat;
import java.text.ParseException;
import java.util.BitSet;
import java.util.Collections;
import java.util.HashSet;
import java.util.Set;

import com.bangcommunity.bbframe.common.utils.Assert;

/**
 * Miscellaneous utility methods for number conversion and parsing. Mainly for internal use within
 * the framework; consider Apache's Commons Lang for a more comprehensive suite of string utilities.
 *
 * @author Juergen Hoeller
 * @author Rob Harrop
 * @since 1.1.2
 */
public abstract class NumberUtils {

    private static final BigInteger LONG_MIN = BigInteger.valueOf(Long.MIN_VALUE);

    private static final BigInteger LONG_MAX = BigInteger.valueOf(Long.MAX_VALUE);

    /**
     * Standard number types (all immutable): Byte, Short, Integer, Long, BigInteger, Float, Double,
     * BigDecimal.
     */
    public static final Set<Class<?>> STANDARD_NUMBER_TYPES;

    static {
        Set<Class<?>> numberTypes = new HashSet<Class<?>>(8);
        numberTypes.add(Byte.class);
        numberTypes.add(Short.class);
        numberTypes.add(Integer.class);
        numberTypes.add(Long.class);
        numberTypes.add(BigInteger.class);
        numberTypes.add(Float.class);
        numberTypes.add(Double.class);
        numberTypes.add(BigDecimal.class);
        STANDARD_NUMBER_TYPES = Collections.unmodifiableSet(numberTypes);
    }

    /**
     * Convert the given number into an instance of the given target class.
     * 
     * @param number
     *            the number to convert
     * @param targetClass
     *            the target class to convert to
     * @return the converted number
     * @throws IllegalArgumentException
     *             if the target class is not supported (i.e. not a standard Number subclass as
     *             included in the JDK)
     * @see Byte
     * @see Short
     * @see Integer
     * @see Long
     * @see BigInteger
     * @see Float
     * @see Double
     * @see BigDecimal
     */
    @SuppressWarnings("unchecked")
    public static <T extends Number> T convertNumberToTargetClass(Number number, Class<T> targetClass)
            throws IllegalArgumentException {

        Assert.notNull(number, "Number must not be null");
        Assert.notNull(targetClass, "Target class must not be null");

        if (targetClass.isInstance(number)) {
            return (T) number;
        } else if (targetClass.equals(Byte.class)) {
            long value = number.longValue();
            if (value < Byte.MIN_VALUE || value > Byte.MAX_VALUE) {
                raiseOverflowException(number, targetClass);
            }
            return (T) new Byte(number.byteValue());
        } else if (targetClass.equals(Short.class)) {
            long value = number.longValue();
            if (value < Short.MIN_VALUE || value > Short.MAX_VALUE) {
                raiseOverflowException(number, targetClass);
            }
            return (T) new Short(number.shortValue());
        } else if (targetClass.equals(Integer.class)) {
            long value = number.longValue();
            if (value < Integer.MIN_VALUE || value > Integer.MAX_VALUE) {
                raiseOverflowException(number, targetClass);
            }
            return (T) new Integer(number.intValue());
        } else if (targetClass.equals(Long.class)) {
            BigInteger bigInt = null;
            if (number instanceof BigInteger) {
                bigInt = (BigInteger) number;
            } else if (number instanceof BigDecimal) {
                bigInt = ((BigDecimal) number).toBigInteger();
            }
            // Effectively analogous to JDK 8's BigInteger.longValueExact()
            if (bigInt != null && (bigInt.compareTo(LONG_MIN) < 0 || bigInt.compareTo(LONG_MAX) > 0)) {
                raiseOverflowException(number, targetClass);
            }
            return (T) new Long(number.longValue());
        } else if (targetClass.equals(BigInteger.class)) {
            if (number instanceof BigDecimal) {
                // do not lose precision - use BigDecimal's own conversion
                return (T) ((BigDecimal) number).toBigInteger();
            } else {
                // original value is not a Big* number - use standard long conversion
                return (T) BigInteger.valueOf(number.longValue());
            }
        } else if (targetClass.equals(Float.class)) {
            return (T) new Float(number.floatValue());
        } else if (targetClass.equals(Double.class)) {
            return (T) new Double(number.doubleValue());
        } else if (targetClass.equals(BigDecimal.class)) {
            // always use BigDecimal(String) here to avoid unpredictability of BigDecimal(double)
            // (see BigDecimal javadoc for details)
            return (T) new BigDecimal(number.toString());
        } else {
            throw new IllegalArgumentException("Could not convert number [" + number + "] of type ["
                    + number.getClass().getName() + "] to unknown target class [" + targetClass.getName() + "]");
        }
    }

    /**
     * Raise an overflow exception for the given number and target class.
     * 
     * @param number
     *            the number we tried to convert
     * @param targetClass
     *            the target class we tried to convert to
     */
    private static void raiseOverflowException(Number number, Class<?> targetClass) {
        throw new IllegalArgumentException("Could not convert number [" + number + "] of type ["
                + number.getClass().getName() + "] to target class [" + targetClass.getName() + "]: overflow");
    }

    /**
     * Parse the given text into a number instance of the given target class, using the
     * corresponding {@code decode} / {@code valueOf} methods.
     * <p>
     * Trims the input {@code String} before attempting to parse the number. Supports numbers in hex
     * format (with leading "0x", "0X" or "#") as well.
     * 
     * @param text
     *            the text to convert
     * @param targetClass
     *            the target class to parse into
     * @return the parsed number
     * @throws IllegalArgumentException
     *             if the target class is not supported (i.e. not a standard Number subclass as
     *             included in the JDK)
     * @see Byte#decode
     * @see Short#decode
     * @see Integer#decode
     * @see Long#decode
     * @see #decodeBigInteger(String)
     * @see Float#valueOf
     * @see Double#valueOf
     * @see BigDecimal#BigDecimal(String)
     */
    @SuppressWarnings("unchecked")
    public static <T extends Number> T parseNumber(String text, Class<T> targetClass) {
        Assert.notNull(text, "Text must not be null");
        Assert.notNull(targetClass, "Target class must not be null");
        String trimmed = StringUtils.trimAllWhitespace(text);

        if (targetClass.equals(Byte.class)) {
            return (T) (isHexNumber(trimmed) ? Byte.decode(trimmed) : Byte.valueOf(trimmed));
        } else if (targetClass.equals(Short.class)) {
            return (T) (isHexNumber(trimmed) ? Short.decode(trimmed) : Short.valueOf(trimmed));
        } else if (targetClass.equals(Integer.class)) {
            return (T) (isHexNumber(trimmed) ? Integer.decode(trimmed) : Integer.valueOf(trimmed));
        } else if (targetClass.equals(Long.class)) {
            return (T) (isHexNumber(trimmed) ? Long.decode(trimmed) : Long.valueOf(trimmed));
        } else if (targetClass.equals(BigInteger.class)) {
            return (T) (isHexNumber(trimmed) ? decodeBigInteger(trimmed) : new BigInteger(trimmed));
        } else if (targetClass.equals(Float.class)) {
            return (T) Float.valueOf(trimmed);
        } else if (targetClass.equals(Double.class)) {
            return (T) Double.valueOf(trimmed);
        } else if (targetClass.equals(BigDecimal.class) || targetClass.equals(Number.class)) {
            return (T) new BigDecimal(trimmed);
        } else {
            throw new IllegalArgumentException(
                    "Cannot convert String [" + text + "] to target class [" + targetClass.getName() + "]");
        }
    }

    /**
     * Parse the given text into a number instance of the given target class, using the given
     * NumberFormat. Trims the input {@code String} before attempting to parse the number.
     * 
     * @param text
     *            the text to convert
     * @param targetClass
     *            the target class to parse into
     * @param numberFormat
     *            the NumberFormat to use for parsing (if {@code null}, this method falls back to
     *            {@code parseNumber(String, Class)})
     * @return the parsed number
     * @throws IllegalArgumentException
     *             if the target class is not supported (i.e. not a standard Number subclass as
     *             included in the JDK)
     * @see NumberFormat#parse
     * @see #convertNumberToTargetClass
     * @see #parseNumber(String, Class)
     */
    public static <T extends Number> T parseNumber(String text, Class<T> targetClass, NumberFormat numberFormat) {
        if (numberFormat != null) {
            Assert.notNull(text, "Text must not be null");
            Assert.notNull(targetClass, "Target class must not be null");
            DecimalFormat decimalFormat = null;
            boolean resetBigDecimal = false;
            if (numberFormat instanceof DecimalFormat) {
                decimalFormat = (DecimalFormat) numberFormat;
                if (BigDecimal.class.equals(targetClass) && !decimalFormat.isParseBigDecimal()) {
                    decimalFormat.setParseBigDecimal(true);
                    resetBigDecimal = true;
                }
            }
            try {
                Number number = numberFormat.parse(StringUtils.trimAllWhitespace(text));
                return convertNumberToTargetClass(number, targetClass);
            } catch (ParseException ex) {
                throw new IllegalArgumentException("Could not parse number: " + ex.getMessage());
            } finally {
                if (resetBigDecimal) {
                    decimalFormat.setParseBigDecimal(false);
                }
            }
        } else {
            return parseNumber(text, targetClass);
        }
    }

    /**
     * Determine whether the given value String indicates a hex number, i.e. needs to be passed into
     * {@code Integer.decode} instead of {@code Integer.valueOf} (etc).
     */
    private static boolean isHexNumber(String value) {
        int index = (value.startsWith("-") ? 1 : 0);
        return (value.startsWith("0x", index) || value.startsWith("0X", index) || value.startsWith("#", index));
    }

    /**
     * 二进制字符串转成十进制long
     */
    public static long binStringToLong(String binary) {
        BigInteger bigInteger = new BigInteger(binary,2);
        return bigInteger.longValue();
    }
    /**
     * 二进制转BitSet
     *
     * @param binary
     * @return
     */
    public static BitSet binaryToBitSet(String binary) {
        BitSet bitSet = new BitSet();
        for (int i = 0; i < binary.length(); i++) {
            String c = String.valueOf(binary.charAt(i));
            if ("1".equals(c)) {
                bitSet.set(i, true);
            }
        }
        return bitSet;
    }
    /**
     * Decode a {@link BigInteger} from a {@link String} value. Supports decimal, hex and octal
     * notation.
     * 
     * @see BigInteger#BigInteger(String, int)
     */
    private static BigInteger decodeBigInteger(String value) {
        int radix = 10;
        int index = 0;
        boolean negative = false;

        // Handle minus sign, if present.
        if (value.startsWith("-")) {
            negative = true;
            index++;
        }

        // Handle radix specifier, if present.
        if (value.startsWith("0x", index) || value.startsWith("0X", index)) {
            index += 2;
            radix = 16;
        } else if (value.startsWith("#", index)) {
            index++;
            radix = 16;
        } else if (value.startsWith("0", index) && value.length() > 1 + index) {
            index++;
            radix = 8;
        }

        BigInteger result = new BigInteger(value.substring(index), radix);
        return (negative ? result.negate() : result);
    }

    /** Reusable Long constant for zero. */
    public static final Long LONG_ZERO = Long.valueOf(0L);
    /** Reusable Long constant for one. */
    public static final Long LONG_ONE = Long.valueOf(1L);
    /** Reusable Long constant for minus one. */
    public static final Long LONG_MINUS_ONE = Long.valueOf(-1L);
    /** Reusable Integer constant for zero. */
    public static final Integer INTEGER_ZERO = Integer.valueOf(0);
    /** Reusable Integer constant for one. */
    public static final Integer INTEGER_ONE = Integer.valueOf(1);
    /** Reusable Integer constant for minus one. */
    public static final Integer INTEGER_MINUS_ONE = Integer.valueOf(-1);
    /** Reusable Short constant for zero. */
    public static final Short SHORT_ZERO = Short.valueOf((short) 0);
    /** Reusable Short constant for one. */
    public static final Short SHORT_ONE = Short.valueOf((short) 1);
    /** Reusable Short constant for minus one. */
    public static final Short SHORT_MINUS_ONE = Short.valueOf((short) -1);
    /** Reusable Byte constant for zero. */
    public static final Byte BYTE_ZERO = Byte.valueOf((byte) 0);
    /** Reusable Byte constant for one. */
    public static final Byte BYTE_ONE = Byte.valueOf((byte) 1);
    /** Reusable Byte constant for minus one. */
    public static final Byte BYTE_MINUS_ONE = Byte.valueOf((byte) -1);
    /** Reusable Double constant for zero. */
    public static final Double DOUBLE_ZERO = Double.valueOf(0.0d);
    /** Reusable Double constant for one. */
    public static final Double DOUBLE_ONE = Double.valueOf(1.0d);
    /** Reusable Double constant for minus one. */
    public static final Double DOUBLE_MINUS_ONE = Double.valueOf(-1.0d);
    /** Reusable Float constant for zero. */
    public static final Float FLOAT_ZERO = Float.valueOf(0.0f);
    /** Reusable Float constant for one. */
    public static final Float FLOAT_ONE = Float.valueOf(1.0f);
    /** Reusable Float constant for minus one. */
    public static final Float FLOAT_MINUS_ONE = Float.valueOf(-1.0f);

    /**
     * <p>
     * <code>NumberUtils</code> instances should NOT be constructed in standard programming.
     * Instead, the class should be used as <code>NumberUtils.toInt("6");</code>.
     * </p>
     *
     * <p>
     * This constructor is public to permit tools that require a JavaBean instance to operate.
     * </p>
     */
    public NumberUtils() {
        super();
    }

    // -----------------------------------------------------------------------
    /**
     * <p>
     * Convert a <code>String</code> to an <code>int</code>, returning <code>zero</code> if the
     * conversion fails.
     * </p>
     *
     * <p>
     * If the string is <code>null</code>, <code>zero</code> is returned.
     * </p>
     *
     * <pre>
     *   NumberUtils.toInt(null) = 0
     *   NumberUtils.toInt("")   = 0
     *   NumberUtils.toInt("1")  = 1
     * </pre>
     *
     * @param str
     *            the string to convert, may be null
     * @return the int represented by the string, or <code>zero</code> if conversion fails
     * @since 2.1
     */
    public static int toInt(final String str) {
        return toInt(str, 0);
    }

    /**
     * <p>
     * Convert a <code>String</code> to an <code>int</code>, returning a default value if the
     * conversion fails.
     * </p>
     *
     * <p>
     * If the string is <code>null</code>, the default value is returned.
     * </p>
     *
     * <pre>
     *   NumberUtils.toInt(null, 1) = 1
     *   NumberUtils.toInt("", 1)   = 1
     *   NumberUtils.toInt("1", 0)  = 1
     * </pre>
     *
     * @param str
     *            the string to convert, may be null
     * @param defaultValue
     *            the default value
     * @return the int represented by the string, or the default if conversion fails
     * @since 2.1
     */
    public static int toInt(final String str, final int defaultValue) {
        if (str == null) {
            return defaultValue;
        }
        try {
            return Integer.parseInt(str);
        } catch (final NumberFormatException nfe) {
            return defaultValue;
        }
    }

    /**
     * <p>
     * Convert a <code>String</code> to a <code>long</code>, returning <code>zero</code> if the
     * conversion fails.
     * </p>
     *
     * <p>
     * If the string is <code>null</code>, <code>zero</code> is returned.
     * </p>
     *
     * <pre>
     *   NumberUtils.toLong(null) = 0L
     *   NumberUtils.toLong("")   = 0L
     *   NumberUtils.toLong("1")  = 1L
     * </pre>
     *
     * @param str
     *            the string to convert, may be null
     * @return the long represented by the string, or <code>0</code> if conversion fails
     * @since 2.1
     */
    public static long toLong(final String str) {
        return toLong(str, 0L);
    }

    /**
     * <p>
     * Convert a <code>String</code> to a <code>long</code>, returning a default value if the
     * conversion fails.
     * </p>
     *
     * <p>
     * If the string is <code>null</code>, the default value is returned.
     * </p>
     *
     * <pre>
     *   NumberUtils.toLong(null, 1L) = 1L
     *   NumberUtils.toLong("", 1L)   = 1L
     *   NumberUtils.toLong("1", 0L)  = 1L
     * </pre>
     *
     * @param str
     *            the string to convert, may be null
     * @param defaultValue
     *            the default value
     * @return the long represented by the string, or the default if conversion fails
     * @since 2.1
     */
    public static long toLong(final String str, final long defaultValue) {
        if (str == null) {
            return defaultValue;
        }
        try {
            return Long.parseLong(str);
        } catch (final NumberFormatException nfe) {
            return defaultValue;
        }
    }

    /**
     * <p>
     * Convert a <code>String</code> to a <code>float</code>, returning <code>0.0f</code> if the
     * conversion fails.
     * </p>
     *
     * <p>
     * If the string <code>str</code> is <code>null</code>, <code>0.0f</code> is returned.
     * </p>
     *
     * <pre>
     *   NumberUtils.toFloat(null)   = 0.0f
     *   NumberUtils.toFloat("")     = 0.0f
     *   NumberUtils.toFloat("1.5")  = 1.5f
     * </pre>
     *
     * @param str
     *            the string to convert, may be <code>null</code>
     * @return the float represented by the string, or <code>0.0f</code> if conversion fails
     * @since 2.1
     */
    public static float toFloat(final String str) {
        return toFloat(str, 0.0f);
    }

    /**
     * <p>
     * Convert a <code>String</code> to a <code>float</code>, returning a default value if the
     * conversion fails.
     * </p>
     *
     * <p>
     * If the string <code>str</code> is <code>null</code>, the default value is returned.
     * </p>
     *
     * <pre>
     *   NumberUtils.toFloat(null, 1.1f)   = 1.0f
     *   NumberUtils.toFloat("", 1.1f)     = 1.1f
     *   NumberUtils.toFloat("1.5", 0.0f)  = 1.5f
     * </pre>
     *
     * @param str
     *            the string to convert, may be <code>null</code>
     * @param defaultValue
     *            the default value
     * @return the float represented by the string, or defaultValue if conversion fails
     * @since 2.1
     */
    public static float toFloat(final String str, final float defaultValue) {
        if (str == null) {
            return defaultValue;
        }
        try {
            return Float.parseFloat(str);
        } catch (final NumberFormatException nfe) {
            return defaultValue;
        }
    }

    /**
     * <p>
     * Convert a <code>String</code> to a <code>double</code>, returning <code>0.0d</code> if the
     * conversion fails.
     * </p>
     *
     * <p>
     * If the string <code>str</code> is <code>null</code>, <code>0.0d</code> is returned.
     * </p>
     *
     * <pre>
     *   NumberUtils.toDouble(null)   = 0.0d
     *   NumberUtils.toDouble("")     = 0.0d
     *   NumberUtils.toDouble("1.5")  = 1.5d
     * </pre>
     *
     * @param str
     *            the string to convert, may be <code>null</code>
     * @return the double represented by the string, or <code>0.0d</code> if conversion fails
     * @since 2.1
     */
    public static double toDouble(final String str) {
        return toDouble(str, 0.0d);
    }

    /**
     * <p>
     * Convert a <code>String</code> to a <code>double</code>, returning a default value if the
     * conversion fails.
     * </p>
     *
     * <p>
     * If the string <code>str</code> is <code>null</code>, the default value is returned.
     * </p>
     *
     * <pre>
     *   NumberUtils.toDouble(null, 1.1d)   = 1.1d
     *   NumberUtils.toDouble("", 1.1d)     = 1.1d
     *   NumberUtils.toDouble("1.5", 0.0d)  = 1.5d
     * </pre>
     *
     * @param str
     *            the string to convert, may be <code>null</code>
     * @param defaultValue
     *            the default value
     * @return the double represented by the string, or defaultValue if conversion fails
     * @since 2.1
     */
    public static double toDouble(final String str, final double defaultValue) {
        if (str == null) {
            return defaultValue;
        }
        try {
            return Double.parseDouble(str);
        } catch (final NumberFormatException nfe) {
            return defaultValue;
        }
    }

    // -----------------------------------------------------------------------
    /**
     * <p>
     * Convert a <code>String</code> to a <code>byte</code>, returning <code>zero</code> if the
     * conversion fails.
     * </p>
     *
     * <p>
     * If the string is <code>null</code>, <code>zero</code> is returned.
     * </p>
     *
     * <pre>
     *   NumberUtils.toByte(null) = 0
     *   NumberUtils.toByte("")   = 0
     *   NumberUtils.toByte("1")  = 1
     * </pre>
     *
     * @param str
     *            the string to convert, may be null
     * @return the byte represented by the string, or <code>zero</code> if conversion fails
     * @since 2.5
     */
    public static byte toByte(final String str) {
        return toByte(str, (byte) 0);
    }

    /**
     * <p>
     * Convert a <code>String</code> to a <code>byte</code>, returning a default value if the
     * conversion fails.
     * </p>
     *
     * <p>
     * If the string is <code>null</code>, the default value is returned.
     * </p>
     *
     * <pre>
     *   NumberUtils.toByte(null, 1) = 1
     *   NumberUtils.toByte("", 1)   = 1
     *   NumberUtils.toByte("1", 0)  = 1
     * </pre>
     *
     * @param str
     *            the string to convert, may be null
     * @param defaultValue
     *            the default value
     * @return the byte represented by the string, or the default if conversion fails
     * @since 2.5
     */
    public static byte toByte(final String str, final byte defaultValue) {
        if (str == null) {
            return defaultValue;
        }
        try {
            return Byte.parseByte(str);
        } catch (final NumberFormatException nfe) {
            return defaultValue;
        }
    }

    /**
     * <p>
     * Convert a <code>String</code> to a <code>short</code>, returning <code>zero</code> if the
     * conversion fails.
     * </p>
     *
     * <p>
     * If the string is <code>null</code>, <code>zero</code> is returned.
     * </p>
     *
     * <pre>
     *   NumberUtils.toShort(null) = 0
     *   NumberUtils.toShort("")   = 0
     *   NumberUtils.toShort("1")  = 1
     * </pre>
     *
     * @param str
     *            the string to convert, may be null
     * @return the short represented by the string, or <code>zero</code> if conversion fails
     * @since 2.5
     */
    public static short toShort(final String str) {
        return toShort(str, (short) 0);
    }

    /**
     * <p>
     * Convert a <code>String</code> to an <code>short</code>, returning a default value if the
     * conversion fails.
     * </p>
     *
     * <p>
     * If the string is <code>null</code>, the default value is returned.
     * </p>
     *
     * <pre>
     *   NumberUtils.toShort(null, 1) = 1
     *   NumberUtils.toShort("", 1)   = 1
     *   NumberUtils.toShort("1", 0)  = 1
     * </pre>
     *
     * @param str
     *            the string to convert, may be null
     * @param defaultValue
     *            the default value
     * @return the short represented by the string, or the default if conversion fails
     * @since 2.5
     */
    public static short toShort(final String str, final short defaultValue) {
        if (str == null) {
            return defaultValue;
        }
        try {
            return Short.parseShort(str);
        } catch (final NumberFormatException nfe) {
            return defaultValue;
        }
    }

    // -----------------------------------------------------------------------
    // must handle Long, Float, Integer, Float, Short,
    // BigDecimal, BigInteger and Byte
    // useful methods:
    // Byte.decode(String)
    // Byte.valueOf(String,int radix)
    // Byte.valueOf(String)
    // Double.valueOf(String)
    // Float.valueOf(String)
    // Float.valueOf(String)
    // Integer.valueOf(String,int radix)
    // Integer.valueOf(String)
    // Integer.decode(String)
    // Integer.getInteger(String)
    // Integer.getInteger(String,int val)
    // Integer.getInteger(String,Integer val)
    // Integer.valueOf(String)
    // Double.valueOf(String)
    // new Byte(String)
    // Long.valueOf(String)
    // Long.getLong(String)
    // Long.getLong(String,int)
    // Long.getLong(String,Integer)
    // Long.valueOf(String,int)
    // Long.valueOf(String)
    // Short.valueOf(String)
    // Short.decode(String)
    // Short.valueOf(String,int)
    // Short.valueOf(String)
    // new BigDecimal(String)
    // new BigInteger(String)
    // new BigInteger(String,int radix)
    // Possible inputs:
    // 45 45.5 45E7 4.5E7 Hex Oct Binary xxxF xxxD xxxf xxxd
    // plus minus everything. Prolly more. A lot are not separable.

    /**
     * <p>
     * Turns a string value into a java.lang.Number.
     * </p>
     *
     * <p>
     * If the string starts with {@code 0x} or {@code -0x} (lower or upper case) or {@code #} or
     * {@code -#}, it will be interpreted as a hexadecimal Integer - or Long, if the number of
     * digits after the prefix is more than 8 - or BigInteger if there are more than 16 digits.
     * </p>
     * <p>
     * Then, the value is examined for a type qualifier on the end, i.e. one of
     * <code>'f','F','d','D','l','L'</code>. If it is found, it starts trying to create successively
     * larger types from the type specified until one is found that can represent the value.
     * </p>
     *
     * <p>
     * If a type specifier is not found, it will check for a decimal point and then try successively
     * larger types from <code>Integer</code> to <code>BigInteger</code> and from <code>Float</code>
     * to <code>BigDecimal</code>.
     * </p>
     *
     * <p>
     * Integral values with a leading {@code 0} will be interpreted as octal; the returned number
     * will be Integer, Long or BigDecimal as appropriate.
     * </p>
     *
     * <p>
     * Returns <code>null</code> if the string is <code>null</code>.
     * </p>
     *
     * <p>
     * This method does not trim the input string, i.e., strings with leading or trailing spaces
     * will generate NumberFormatExceptions.
     * </p>
     *
     * @param str
     *            String containing a number, may be null
     * @return Number created from the string (or null if the input is null)
     * @throws NumberFormatException
     *             if the value cannot be converted
     */
    public static Number createNumber(final String str) throws NumberFormatException {
        if (str == null) {
            return null;
        }
        if (StringUtils.isBlank(str)) {
            throw new NumberFormatException("A blank string is not a valid number");
        }
        // Need to deal with all possible hex prefixes here
        final String[] hex_prefixes = { "0x", "0X", "-0x", "-0X", "#", "-#" };
        int pfxLen = 0;
        for (final String pfx : hex_prefixes) {
            if (str.startsWith(pfx)) {
                pfxLen += pfx.length();
                break;
            }
        }
        if (pfxLen > 0) { // we have a hex number
            char firstSigDigit = 0; // strip leading zeroes
            for (int i = pfxLen; i < str.length(); i++) {
                firstSigDigit = str.charAt(i);
                if (firstSigDigit == '0') { // count leading zeroes
                    pfxLen++;
                } else {
                    break;
                }
            }
            final int hexDigits = str.length() - pfxLen;
            if (hexDigits > 16 || (hexDigits == 16 && firstSigDigit > '7')) { // too many for Long
                return createBigInteger(str);
            }
            if (hexDigits > 8 || (hexDigits == 8 && firstSigDigit > '7')) { // too many for an int
                return createLong(str);
            }
            return createInteger(str);
        }
        final char lastChar = str.charAt(str.length() - 1);
        String mant;
        String dec;
        String exp;
        final int decPos = str.indexOf('.');
        final int expPos = str.indexOf('e') + str.indexOf('E') + 1; // assumes both not present
        // if both e and E are present, this is caught by the checks on expPos (which prevent IOOBE)
        // and the parsing which will detect if e or E appear in a number due to using the wrong
        // offset

        int numDecimals = 0; // Check required precision (LANG-693)
        if (decPos > -1) { // there is a decimal point

            if (expPos > -1) { // there is an exponent
                if (expPos < decPos || expPos > str.length()) { // prevents double exponent causing
                                                                // IOOBE
                    throw new NumberFormatException(str + " is not a valid number.");
                }
                dec = str.substring(decPos + 1, expPos);
            } else {
                dec = str.substring(decPos + 1);
            }
            mant = str.substring(0, decPos);
            numDecimals = dec.length(); // gets number of digits past the decimal to ensure no loss
                                        // of precision for floating point numbers.
        } else {
            if (expPos > -1) {
                if (expPos > str.length()) { // prevents double exponent causing IOOBE
                    throw new NumberFormatException(str + " is not a valid number.");
                }
                mant = str.substring(0, expPos);
            } else {
                mant = str;
            }
            dec = null;
        }
        if (!Character.isDigit(lastChar) && lastChar != '.') {
            if (expPos > -1 && expPos < str.length() - 1) {
                exp = str.substring(expPos + 1, str.length() - 1);
            } else {
                exp = null;
            }
            // Requesting a specific type..
            final String numeric = str.substring(0, str.length() - 1);
            final boolean allZeros = isAllZeros(mant) && isAllZeros(exp);
            switch (lastChar) {
            case 'l':
            case 'L':
                if (dec == null && exp == null
                        && (numeric.charAt(0) == '-' && isDigits(numeric.substring(1)) || isDigits(numeric))) {
                    try {
                        return createLong(numeric);
                    } catch (final NumberFormatException nfe) { // NOPMD
                        // Too big for a long
                    }
                    return createBigInteger(numeric);

                }
                throw new NumberFormatException(str + " is not a valid number.");
            case 'f':
            case 'F':
                try {
                    final Float f = NumberUtils.createFloat(numeric);
                    if (!(f.isInfinite() || (f.floatValue() == 0.0F && !allZeros))) {
                        // If it's too big for a float or the float value = 0 and the string
                        // has non-zeros in it, then float does not have the precision we want
                        return f;
                    }

                } catch (final NumberFormatException nfe) { // NOPMD
                    // ignore the bad number
                }
                //$FALL-THROUGH$
            case 'd':
            case 'D':
                try {
                    final Double d = NumberUtils.createDouble(numeric);
                    if (!(d.isInfinite() || (d.floatValue() == 0.0D && !allZeros))) {
                        return d;
                    }
                } catch (final NumberFormatException nfe) { // NOPMD
                    // ignore the bad number
                }
                try {
                    return createBigDecimal(numeric);
                } catch (final NumberFormatException e) { // NOPMD
                    // ignore the bad number
                }
                //$FALL-THROUGH$
            default:
                throw new NumberFormatException(str + " is not a valid number.");

            }
        }
        // User doesn't have a preference on the return type, so let's start
        // small and go from there...
        if (expPos > -1 && expPos < str.length() - 1) {
            exp = str.substring(expPos + 1, str.length());
        } else {
            exp = null;
        }
        if (dec == null && exp == null) { // no decimal point and no exponent
            // Must be an Integer, Long, Biginteger
            try {
                return createInteger(str);
            } catch (final NumberFormatException nfe) { // NOPMD
                // ignore the bad number
            }
            try {
                return createLong(str);
            } catch (final NumberFormatException nfe) { // NOPMD
                // ignore the bad number
            }
            return createBigInteger(str);
        }

        // Must be a Float, Double, BigDecimal
        final boolean allZeros = isAllZeros(mant) && isAllZeros(exp);
        try {
            if (numDecimals <= 7) {// If number has 7 or fewer digits past the decimal point then
                                   // make it a float
                final Float f = createFloat(str);
                if (!(f.isInfinite() || (f.floatValue() == 0.0F && !allZeros))) {
                    return f;
                }
            }
        } catch (final NumberFormatException nfe) { // NOPMD
            // ignore the bad number
        }
        try {
            if (numDecimals <= 16) {// If number has between 8 and 16 digits past the decimal point
                                    // then make it a double
                final Double d = createDouble(str);
                if (!(d.isInfinite() || (d.doubleValue() == 0.0D && !allZeros))) {
                    return d;
                }
            }
        } catch (final NumberFormatException nfe) { // NOPMD
            // ignore the bad number
        }

        return createBigDecimal(str);
    }

    /**
     * <p>
     * Utility method for {@link #createNumber(java.lang.String)}.
     * </p>
     *
     * <p>
     * Returns <code>true</code> if s is <code>null</code>.
     * </p>
     *
     * @param str
     *            the String to check
     * @return if it is all zeros or <code>null</code>
     */
    private static boolean isAllZeros(final String str) {
        if (str == null) {
            return true;
        }
        for (int i = str.length() - 1; i >= 0; i--) {
            if (str.charAt(i) != '0') {
                return false;
            }
        }
        return str.length() > 0;
    }

    // -----------------------------------------------------------------------
    /**
     * <p>
     * Convert a <code>String</code> to a <code>Float</code>.
     * </p>
     *
     * <p>
     * Returns <code>null</code> if the string is <code>null</code>.
     * </p>
     *
     * @param str
     *            a <code>String</code> to convert, may be null
     * @return converted <code>Float</code> (or null if the input is null)
     * @throws NumberFormatException
     *             if the value cannot be converted
     */
    public static Float createFloat(final String str) {
        if (str == null) {
            return null;
        }
        return Float.valueOf(str);
    }

    /**
     * <p>
     * Convert a <code>String</code> to a <code>Double</code>.
     * </p>
     *
     * <p>
     * Returns <code>null</code> if the string is <code>null</code>.
     * </p>
     *
     * @param str
     *            a <code>String</code> to convert, may be null
     * @return converted <code>Double</code> (or null if the input is null)
     * @throws NumberFormatException
     *             if the value cannot be converted
     */
    public static Double createDouble(final String str) {
        if (str == null) {
            return null;
        }
        return Double.valueOf(str);
    }

    /**
     * <p>
     * Convert a <code>String</code> to a <code>Integer</code>, handling hex and octal notations.
     * </p>
     *
     * <p>
     * Returns <code>null</code> if the string is <code>null</code>.
     * </p>
     *
     * @param str
     *            a <code>String</code> to convert, may be null
     * @return converted <code>Integer</code> (or null if the input is null)
     * @throws NumberFormatException
     *             if the value cannot be converted
     */
    public static Integer createInteger(final String str) {
        if (str == null) {
            return null;
        }
        // decode() handles 0xAABD and 0777 (hex and octal) as well.
        return Integer.decode(str);
    }

    /**
     * <p>
     * Convert a <code>String</code> to a <code>Long</code>; since 3.1 it handles hex and octal
     * notations.
     * </p>
     *
     * <p>
     * Returns <code>null</code> if the string is <code>null</code>.
     * </p>
     *
     * @param str
     *            a <code>String</code> to convert, may be null
     * @return converted <code>Long</code> (or null if the input is null)
     * @throws NumberFormatException
     *             if the value cannot be converted
     */
    public static Long createLong(final String str) {
        if (str == null) {
            return null;
        }
        return Long.decode(str);
    }

    /**
     * <p>
     * Convert a <code>String</code> to a <code>BigInteger</code>; since 3.2 it handles hex (0x or
     * #) and octal (0) notations.
     * </p>
     *
     * <p>
     * Returns <code>null</code> if the string is <code>null</code>.
     * </p>
     *
     * @param str
     *            a <code>String</code> to convert, may be null
     * @return converted <code>BigInteger</code> (or null if the input is null)
     * @throws NumberFormatException
     *             if the value cannot be converted
     */
    public static BigInteger createBigInteger(final String str) {
        if (str == null) {
            return null;
        }
        int pos = 0; // offset within string
        int radix = 10;
        boolean negate = false; // need to negate later?
        if (str.startsWith("-")) {
            negate = true;
            pos = 1;
        }
        if (str.startsWith("0x", pos) || str.startsWith("0x", pos)) { // hex
            radix = 16;
            pos += 2;
        } else if (str.startsWith("#", pos)) { // alternative hex (allowed by Long/Integer)
            radix = 16;
            pos++;
        } else if (str.startsWith("0", pos) && str.length() > pos + 1) { // octal; so long as there
                                                                         // are additional digits
            radix = 8;
            pos++;
        } // default is to treat as decimal

        final BigInteger value = new BigInteger(str.substring(pos), radix);
        return negate ? value.negate() : value;
    }

    /**
     * <p>
     * Convert a <code>String</code> to a <code>BigDecimal</code>.
     * </p>
     *
     * <p>
     * Returns <code>null</code> if the string is <code>null</code>.
     * </p>
     *
     * @param str
     *            a <code>String</code> to convert, may be null
     * @return converted <code>BigDecimal</code> (or null if the input is null)
     * @throws NumberFormatException
     *             if the value cannot be converted
     */
    public static BigDecimal createBigDecimal(final String str) {
        if (str == null) {
            return null;
        }
        // handle JDK1.3.1 bug where "" throws IndexOutOfBoundsException
        if (StringUtils.isBlank(str)) {
            throw new NumberFormatException("A blank string is not a valid number");
        }
        if (str.trim().startsWith("--")) {
            // this is protection for poorness in java.lang.BigDecimal.
            // it accepts this as a legal value, but it does not appear
            // to be in specification of class. OS X Java parses it to
            // a wrong value.
            throw new NumberFormatException(str + " is not a valid number.");
        }
        return new BigDecimal(str);
    }

    // Min in array
    // --------------------------------------------------------------------
    /**
     * <p>
     * Returns the minimum value in an array.
     * </p>
     *
     * @param array
     *            an array, must not be null or empty
     * @return the minimum value in the array
     * @throws IllegalArgumentException
     *             if <code>array</code> is <code>null</code>
     * @throws IllegalArgumentException
     *             if <code>array</code> is empty
     */
    public static long min(final long[] array) {
        // Validates input
        validateArray(array);

        // Finds and returns min
        long min = array[0];
        for (int i = 1; i < array.length; i++) {
            if (array[i] < min) {
                min = array[i];
            }
        }

        return min;
    }

    /**
     * <p>
     * Returns the minimum value in an array.
     * </p>
     *
     * @param array
     *            an array, must not be null or empty
     * @return the minimum value in the array
     * @throws IllegalArgumentException
     *             if <code>array</code> is <code>null</code>
     * @throws IllegalArgumentException
     *             if <code>array</code> is empty
     */
    public static int min(final int[] array) {
        // Validates input
        validateArray(array);

        // Finds and returns min
        int min = array[0];
        for (int j = 1; j < array.length; j++) {
            if (array[j] < min) {
                min = array[j];
            }
        }

        return min;
    }

    /**
     * <p>
     * Returns the minimum value in an array.
     * </p>
     *
     * @param array
     *            an array, must not be null or empty
     * @return the minimum value in the array
     * @throws IllegalArgumentException
     *             if <code>array</code> is <code>null</code>
     * @throws IllegalArgumentException
     *             if <code>array</code> is empty
     */
    public static short min(final short[] array) {
        // Validates input
        validateArray(array);

        // Finds and returns min
        short min = array[0];
        for (int i = 1; i < array.length; i++) {
            if (array[i] < min) {
                min = array[i];
            }
        }

        return min;
    }

    /**
     * <p>
     * Returns the minimum value in an array.
     * </p>
     *
     * @param array
     *            an array, must not be null or empty
     * @return the minimum value in the array
     * @throws IllegalArgumentException
     *             if <code>array</code> is <code>null</code>
     * @throws IllegalArgumentException
     *             if <code>array</code> is empty
     */
    public static byte min(final byte[] array) {
        // Validates input
        validateArray(array);

        // Finds and returns min
        byte min = array[0];
        for (int i = 1; i < array.length; i++) {
            if (array[i] < min) {
                min = array[i];
            }
        }

        return min;
    }

    /**
     * <p>
     * Returns the minimum value in an array.
     * </p>
     *
     * @param array
     *            an array, must not be null or empty
     * @return the minimum value in the array
     * @throws IllegalArgumentException
     *             if <code>array</code> is <code>null</code>
     * @throws IllegalArgumentException
     *             if <code>array</code> is empty
     *      differently
     */
    public static double min(final double[] array) {
        // Validates input
        validateArray(array);

        // Finds and returns min
        double min = array[0];
        for (int i = 1; i < array.length; i++) {
            if (Double.isNaN(array[i])) {
                return Double.NaN;
            }
            if (array[i] < min) {
                min = array[i];
            }
        }

        return min;
    }

    /**
     * <p>
     * Returns the minimum value in an array.
     * </p>
     *
     * @param array
     *            an array, must not be null or empty
     * @return the minimum value in the array
     * @throws IllegalArgumentException
     *             if <code>array</code> is <code>null</code>
     * @throws IllegalArgumentException
     *             if <code>array</code> is empty
     * @see IEEE754rUtils#min(float[]) IEEE754rUtils for a version of this method that handles NaN
     *      differently
     */
    public static float min(final float[] array) {
        // Validates input
        validateArray(array);

        // Finds and returns min
        float min = array[0];
        for (int i = 1; i < array.length; i++) {
            if (Float.isNaN(array[i])) {
                return Float.NaN;
            }
            if (array[i] < min) {
                min = array[i];
            }
        }

        return min;
    }

    // Max in array
    // --------------------------------------------------------------------
    /**
     * <p>
     * Returns the maximum value in an array.
     * </p>
     *
     * @param array
     *            an array, must not be null or empty
     * @return the minimum value in the array
     * @throws IllegalArgumentException
     *             if <code>array</code> is <code>null</code>
     * @throws IllegalArgumentException
     *             if <code>array</code> is empty
     */
    public static long max(final long[] array) {
        // Validates input
        validateArray(array);

        // Finds and returns max
        long max = array[0];
        for (int j = 1; j < array.length; j++) {
            if (array[j] > max) {
                max = array[j];
            }
        }

        return max;
    }

    /**
     * <p>
     * Returns the maximum value in an array.
     * </p>
     *
     * @param array
     *            an array, must not be null or empty
     * @return the minimum value in the array
     * @throws IllegalArgumentException
     *             if <code>array</code> is <code>null</code>
     * @throws IllegalArgumentException
     *             if <code>array</code> is empty
     */
    public static int max(final int[] array) {
        // Validates input
        validateArray(array);

        // Finds and returns max
        int max = array[0];
        for (int j = 1; j < array.length; j++) {
            if (array[j] > max) {
                max = array[j];
            }
        }

        return max;
    }

    /**
     * <p>
     * Returns the maximum value in an array.
     * </p>
     *
     * @param array
     *            an array, must not be null or empty
     * @return the minimum value in the array
     * @throws IllegalArgumentException
     *             if <code>array</code> is <code>null</code>
     * @throws IllegalArgumentException
     *             if <code>array</code> is empty
     */
    public static short max(final short[] array) {
        // Validates input
        validateArray(array);

        // Finds and returns max
        short max = array[0];
        for (int i = 1; i < array.length; i++) {
            if (array[i] > max) {
                max = array[i];
            }
        }

        return max;
    }

    /**
     * <p>
     * Returns the maximum value in an array.
     * </p>
     *
     * @param array
     *            an array, must not be null or empty
     * @return the minimum value in the array
     * @throws IllegalArgumentException
     *             if <code>array</code> is <code>null</code>
     * @throws IllegalArgumentException
     *             if <code>array</code> is empty
     */
    public static byte max(final byte[] array) {
        // Validates input
        validateArray(array);

        // Finds and returns max
        byte max = array[0];
        for (int i = 1; i < array.length; i++) {
            if (array[i] > max) {
                max = array[i];
            }
        }

        return max;
    }

    /**
     * <p>
     * Returns the maximum value in an array.
     * </p>
     *
     * @param array
     *            an array, must not be null or empty
     * @return the minimum value in the array
     * @throws IllegalArgumentException
     *             if <code>array</code> is <code>null</code>
     * @throws IllegalArgumentException
     *             if <code>array</code> is empty
     * @see IEEE754rUtils#max(double[]) IEEE754rUtils for a version of this method that handles NaN
     *      differently
     */
    public static double max(final double[] array) {
        // Validates input
        validateArray(array);

        // Finds and returns max
        double max = array[0];
        for (int j = 1; j < array.length; j++) {
            if (Double.isNaN(array[j])) {
                return Double.NaN;
            }
            if (array[j] > max) {
                max = array[j];
            }
        }

        return max;
    }

    /**
     * <p>
     * Returns the maximum value in an array.
     * </p>
     *
     * @param array
     *            an array, must not be null or empty
     * @return the minimum value in the array
     * @throws IllegalArgumentException
     *             if <code>array</code> is <code>null</code>
     * @throws IllegalArgumentException
     *             if <code>array</code> is empty
     * @see IEEE754rUtils#max(float[]) IEEE754rUtils for a version of this method that handles NaN
     *      differently
     */
    public static float max(final float[] array) {
        // Validates input
        validateArray(array);

        // Finds and returns max
        float max = array[0];
        for (int j = 1; j < array.length; j++) {
            if (Float.isNaN(array[j])) {
                return Float.NaN;
            }
            if (array[j] > max) {
                max = array[j];
            }
        }

        return max;
    }

    /**
     * Checks if the specified array is neither null nor empty.
     *
     * @param array
     *            the array to check
     * @throws IllegalArgumentException
     *             if {@code array} is either {@code null} or empty
     */
    private static void validateArray(final Object array) {
        if (array == null) {
            throw new IllegalArgumentException("The Array must not be null");
        } else if (Array.getLength(array) == 0) {
            throw new IllegalArgumentException("Array cannot be empty.");
        }
    }

    // 3 param min
    // -----------------------------------------------------------------------
    /**
     * <p>
     * Gets the minimum of three <code>long</code> values.
     * </p>
     *
     * @param a
     *            value 1
     * @param b
     *            value 2
     * @param c
     *            value 3
     * @return the smallest of the values
     */
    public static long min(long a, final long b, final long c) {
        if (b < a) {
            a = b;
        }
        if (c < a) {
            a = c;
        }
        return a;
    }

    /**
     * <p>
     * Gets the minimum of three <code>int</code> values.
     * </p>
     *
     * @param a
     *            value 1
     * @param b
     *            value 2
     * @param c
     *            value 3
     * @return the smallest of the values
     */
    public static int min(int a, final int b, final int c) {
        if (b < a) {
            a = b;
        }
        if (c < a) {
            a = c;
        }
        return a;
    }

    /**
     * <p>
     * Gets the minimum of three <code>short</code> values.
     * </p>
     *
     * @param a
     *            value 1
     * @param b
     *            value 2
     * @param c
     *            value 3
     * @return the smallest of the values
     */
    public static short min(short a, final short b, final short c) {
        if (b < a) {
            a = b;
        }
        if (c < a) {
            a = c;
        }
        return a;
    }

    /**
     * <p>
     * Gets the minimum of three <code>byte</code> values.
     * </p>
     *
     * @param a
     *            value 1
     * @param b
     *            value 2
     * @param c
     *            value 3
     * @return the smallest of the values
     */
    public static byte min(byte a, final byte b, final byte c) {
        if (b < a) {
            a = b;
        }
        if (c < a) {
            a = c;
        }
        return a;
    }

    /**
     * <p>
     * Gets the minimum of three <code>double</code> values.
     * </p>
     *
     * <p>
     * If any value is <code>NaN</code>, <code>NaN</code> is returned. Infinity is handled.
     * </p>
     *
     * @param a
     *            value 1
     * @param b
     *            value 2
     * @param c
     *            value 3
     * @return the smallest of the values
     * @see IEEE754rUtils#min(double, double, double) for a version of this method that handles NaN
     *      differently
     */
    public static double min(final double a, final double b, final double c) {
        return Math.min(Math.min(a, b), c);
    }

    /**
     * <p>
     * Gets the minimum of three <code>float</code> values.
     * </p>
     *
     * <p>
     * If any value is <code>NaN</code>, <code>NaN</code> is returned. Infinity is handled.
     * </p>
     *
     * @param a
     *            value 1
     * @param b
     *            value 2
     * @param c
     *            value 3
     * @return the smallest of the values
     * @see IEEE754rUtils#min(float, float, float) for a version of this method that handles NaN
     *      differently
     */
    public static float min(final float a, final float b, final float c) {
        return Math.min(Math.min(a, b), c);
    }

    // 3 param max
    // -----------------------------------------------------------------------
    /**
     * <p>
     * Gets the maximum of three <code>long</code> values.
     * </p>
     *
     * @param a
     *            value 1
     * @param b
     *            value 2
     * @param c
     *            value 3
     * @return the largest of the values
     */
    public static long max(long a, final long b, final long c) {
        if (b > a) {
            a = b;
        }
        if (c > a) {
            a = c;
        }
        return a;
    }

    /**
     * <p>
     * Gets the maximum of three <code>int</code> values.
     * </p>
     *
     * @param a
     *            value 1
     * @param b
     *            value 2
     * @param c
     *            value 3
     * @return the largest of the values
     */
    public static int max(int a, final int b, final int c) {
        if (b > a) {
            a = b;
        }
        if (c > a) {
            a = c;
        }
        return a;
    }

    /**
     * <p>
     * Gets the maximum of three <code>short</code> values.
     * </p>
     *
     * @param a
     *            value 1
     * @param b
     *            value 2
     * @param c
     *            value 3
     * @return the largest of the values
     */
    public static short max(short a, final short b, final short c) {
        if (b > a) {
            a = b;
        }
        if (c > a) {
            a = c;
        }
        return a;
    }

    /**
     * <p>
     * Gets the maximum of three <code>byte</code> values.
     * </p>
     *
     * @param a
     *            value 1
     * @param b
     *            value 2
     * @param c
     *            value 3
     * @return the largest of the values
     */
    public static byte max(byte a, final byte b, final byte c) {
        if (b > a) {
            a = b;
        }
        if (c > a) {
            a = c;
        }
        return a;
    }

    /**
     * <p>
     * Gets the maximum of three <code>double</code> values.
     * </p>
     *
     * <p>
     * If any value is <code>NaN</code>, <code>NaN</code> is returned. Infinity is handled.
     * </p>
     *
     * @param a
     *            value 1
     * @param b
     *            value 2
     * @param c
     *            value 3
     * @return the largest of the values
     * @see IEEE754rUtils#max(double, double, double) for a version of this method that handles NaN
     *      differently
     */
    public static double max(final double a, final double b, final double c) {
        return Math.max(Math.max(a, b), c);
    }

    /**
     * <p>
     * Gets the maximum of three <code>float</code> values.
     * </p>
     *
     * <p>
     * If any value is <code>NaN</code>, <code>NaN</code> is returned. Infinity is handled.
     * </p>
     *
     * @param a
     *            value 1
     * @param b
     *            value 2
     * @param c
     *            value 3
     * @return the largest of the values
     * @see IEEE754rUtils#max(float, float, float) for a version of this method that handles NaN
     *      differently
     */
    public static float max(final float a, final float b, final float c) {
        return Math.max(Math.max(a, b), c);
    }

    // -----------------------------------------------------------------------
    /**
     * <p>
     * Checks whether the <code>String</code> contains only digit characters.
     * </p>
     *
     * <p>
     * <code>Null</code> and empty String will return <code>false</code>.
     * </p>
     *
     * @param str
     *            the <code>String</code> to check
     * @return <code>true</code> if str contains only Unicode numeric
     */
    public static boolean isDigits(final String str) {
        if (StringUtils.isEmpty(str)) {
            return false;
        }
        for (int i = 0; i < str.length(); i++) {
            if (!Character.isDigit(str.charAt(i))) {
                return false;
            }
        }
        return true;
    }

    /**
     * <p>
     * Checks whether the String a valid Java number.
     * </p>
     *
     * <p>
     * Valid numbers include hexadecimal marked with the <code>0x</code> qualifier, scientific
     * notation and numbers marked with a type qualifier (e.g. 123L).
     * </p>
     *
     * <p>
     * <code>Null</code> and empty String will return <code>false</code>.
     * </p>
     *
     * @param str
     *            the <code>String</code> to check
     * @return <code>true</code> if the string is a correctly formatted number
     */
    public static boolean isNumber(final String str) {
        if (StringUtils.isEmpty(str)) {
            return false;
        }
        final char[] chars = str.toCharArray();
        int sz = chars.length;
        boolean hasExp = false;
        boolean hasDecPoint = false;
        boolean allowSigns = false;
        boolean foundDigit = false;
        // deal with any possible sign up front
        final int start = (chars[0] == '-') ? 1 : 0;
        if (sz > start + 1 && chars[start] == '0' && chars[start + 1] == 'x') {
            int i = start + 2;
            if (i == sz) {
                return false; // str == "0x"
            }
            // checking hex (it can't be anything else)
            for (; i < chars.length; i++) {
                if ((chars[i] < '0' || chars[i] > '9') && (chars[i] < 'a' || chars[i] > 'f')
                        && (chars[i] < 'A' || chars[i] > 'F')) {
                    return false;
                }
            }
            return true;
        }
        sz--; // don't want to loop to the last char, check it afterwords
        // for type qualifiers
        int i = start;
        // loop to the next to last char or to the last char if we need another digit to
        // make a valid number (e.g. chars[0..5] = "1234E")
        while (i < sz || (i < sz + 1 && allowSigns && !foundDigit)) {
            if (chars[i] >= '0' && chars[i] <= '9') {
                foundDigit = true;
                allowSigns = false;

            } else if (chars[i] == '.') {
                if (hasDecPoint || hasExp) {
                    // two decimal points or dec in exponent
                    return false;
                }
                hasDecPoint = true;
            } else if (chars[i] == 'e' || chars[i] == 'E') {
                // we've already taken care of hex.
                if (hasExp) {
                    // two E's
                    return false;
                }
                if (!foundDigit) {
                    return false;
                }
                hasExp = true;
                allowSigns = true;
            } else if (chars[i] == '+' || chars[i] == '-') {
                if (!allowSigns) {
                    return false;
                }
                allowSigns = false;
                foundDigit = false; // we need a digit after the E
            } else {
                return false;
            }
            i++;
        }
        if (i < chars.length) {
            if (chars[i] >= '0' && chars[i] <= '9') {
                // no type qualifier, OK
                return true;
            }
            if (chars[i] == 'e' || chars[i] == 'E') {
                // can't have an E at the last byte
                return false;
            }
            if (chars[i] == '.') {
                if (hasDecPoint || hasExp) {
                    // two decimal points or dec in exponent
                    return false;
                }
                // single trailing decimal point after non-exponent is ok
                return foundDigit;
            }
            if (!allowSigns && (chars[i] == 'd' || chars[i] == 'D' || chars[i] == 'f' || chars[i] == 'F')) {
                return foundDigit;
            }
            if (chars[i] == 'l' || chars[i] == 'L') {
                // not allowing L with an exponent or decimal point
                return foundDigit && !hasExp && !hasDecPoint;
            }
            // last character is illegal
            return false;
        }
        // allowSigns is true iff the val ends in 'E'
        // found digit it to make sure weird stuff like '.' and '1E-' doesn't pass
        return !allowSigns && foundDigit;
    }

    public static void main(String[] args) {
        System.out.println(binStringToLong("100"));
        System.out.println(binStringToLong("0100"));
        System.out.println(binStringToLong("0100000000000000000000000000000000000"));
        System.out.println(binStringToLong("01000000000000000000000000000000000000"));
    }
}
